I think Alexander the Great should be known as so for many reasons. One reason being that he served as king of Macedonia from 336 to 323 B.C. During his time of leadership, he united Greece, reestablished the Corinthian League and conquered the Persian Empire.
Alexander the Great build the Largest empire in ancient civil actions in the 33 years he was alive. He lead Greece to their golden age. Hope this helped!
The Union victory did solve a handful of problems, it abolished slavery and get rid of the Confederate Union but not every problem could be solved. Personally I would disagree because the Civil War had other problems right after because of the victory.